1. Field of the Invention
The present invention relates to a liquid channel structure and a liquid-droplet jetting apparatus which jets liquid droplets.
2. Description of the Related Art
In an ink-jet head which jets droplets of ink from a nozzle, if an ink channel has a bent portion, bubbles easily stay or remain in the bent portion. Bubbles are not easily discharged even by purging which forcibly discharges the ink from the nozzle. The bubbles existing in the ink channel hinder the application of a sufficient jetting pressure to the ink in the ink channel and will be a cause of non-discharge or discharge failure of the ink. Therefore, there has conventionally been proposed an ink-jet head which is structured to prevent the bubbles from staying in the bent portion of the ink channel.
For example, U.S. Pat. No. 6,846,069 (corresponding to Japanese Patent Application Laid-open No. 2003-326706) discloses an ink-jet head with the following structure. This ink-jet head has ink channels each extending from a common ink chamber to a nozzle via a pressure chamber. Between the common ink chamber and the pressure chamber, a throttled portion is provided and the ink flows in the throttled portion and the pressure chamber in mutually opposite directions. Further, the throttled portion and the pressure chamber communicate with each other via an ink supply hole. That is, the ink channel is folded back at the ink supply hole between the throttled portion and the pressure chamber. Here, the ink supply hole extends in a direction inclined to the flow direction of the ink. Therefore, the ink in the ink supply hole flows into an end portion of the pressure chamber toward a wall surface of the pressure chamber, and consequently, bubbles are prevented from staying in the bent portion connecting the pressure chamber and the ink supply hole.
According to the ink channel structure of the abovementioned U.S. Pat. No. 6,846,069, although the bubbles staying in the bent portion can be reduced to some extent, the preventing function is not sufficient. Therefore, a channel structure capable of more surely preventing the bubbles from staying is being demanded.